“…Analysis of the microstructures reveals that DNNT grains are inhomogeneous and their average grain size decreases on increasing the level of the dopant up to x = 0.2 mol, and above 0.2 mol, the growth of the grain appears, as shown in Figure a–e. The decreasing grain size with the increase of the Dy 3+ ions suggests that a limited amount of up to 0.2 mol of Dy 3+ ion is enough to enhance the microstructure desired for storage purposes, above which deterioration of the storage character, in this case, grain size, which is inversely related to the breakdown strength of the materials, in question is assured . The grain size for various x contents is as follows: for 0, 0.05, 0.1, 0.2, and 0.3 it is 5.22 ± 0.2, 1.44 ± 0.2, 1.31 ± 0.2, 1.10 ± 0.2, and 1.44 ± 0.2 μm, respectively, as shown in Figure f.…”